By the way, I have in the end decided to go with the JPAN's patch upon seeing the tutorial for making custom items. I plan to utilise a lot more of the features in the future, so keep an eye open for them. :3

Wow, I really love the dark pallet you used in Ash Tunnel, and Ash Town look pretty unique as well. There is a small tile error in your second Ash Tunnel screenshot - The rock wall above the ladder is meant to go over regular ground, rather than sand (if you know what I mean). Heatran's OW looks perfect and I can't wait to see him in battle :>